CCD photometric study of the W UMa-type binary II CMa in the field of Berkeley 33

TL;DR

This study presents CCD photometry and analysis of the W UMa-type binary II CMa, revealing it as a marginal contact system with a high mass ratio and low contact degree, in the field of Berkeley 33.

Contribution

The paper provides new CCD photometric data and a revised orbital period for II CMa, analyzing its contact configuration using the Wilson-Devinney method.

Findings

Revised orbital period to 0.22919704 days.

Identified as a marginal contact system with q=0.9.

Contact factor determined to be 4.1%.

Abstract

The CCD photometric data of the EW-type binary, II CMa, which is a contact star in the field of the middle-aged open cluster Berkeley 33, are presented. The complete R light curve was obtained. In the present paper, using the five CCD epochs of light minimum (three of them are calculated from Mazur et al. (1993)'s data and two from our new data), the orbital period P was revised to 0.22919704 days. The complete R light curve was analyzed by using the 2003 version of W-D (Wilson-Devinney) program. It is found that this is a contact system with a mass ratio $q=0.9$ and a contact factor $f=4.1%$. The high mass ratio ($q=0.9$) and the low contact factor ($f=4.1%$) indicate that the system just evolved into the marginal contact stage.